Agonizing torture at the hands of the secret police threatens any citizen who resists in a Hungary subjugated by the ruthless dictator Joseph Stalin. Cardinal Josef Mindszenty (Charles Bickford), taking a courageous open stand against the Communists, is labeled a traitor by the brutal regime bent on crushing all opposition. Intrigued by whispers of what may be going on inside the Soviet-occupied nation, American foreign correspondent Tom Kelly shows up in Budapest to investigate.
Shortly after arriving, he is introduced to beautiful Stephanie Varna (Bonita Granville), a Hungarian schoolteacher who is secretly involved with a Russian colonel. She manages to lead Tom to the Cardinal only days before he is thrown into prison, while a wave of false arrests and mysterious disappearances envelops the brave souls who dared to follow the Cardinal's anti-Communist lead.
This film showcases gruff-voiced Charles Bickford whose work includes Of Mice and Men (1939) and the acclaimed Days of Wine and Roses (1962). Inspired by the true story of Cardinal Mindszenty's persecution and trial in Hungary, the documentary/propaganda style of Guilty of Treason examines the Hungarian Communist regime which rose to power after Nazi rule.